1. Field of the Invention
The present invention relates to an apparatus for and a method of purging remaining gas in the pipe of a cylinder cabinet.
2. Description of the Related Art
A conventional cylinder cabinet will be described making use of FIG. 1 because it is the same as that according to a first embodiment of the present invention.
Conventionally, a method of purging gas remaining in a primary pipe 14 of a cylinder cabinet is mainly executed manually. That is, leaving-pipe-in-pressurized-state purge is repeated manually to pressurize the inside of the primary pipe 14 by inert gas 15 and to leave it in the pressurized state for 5 to 30 seconds and to evacuate the primary pipe 14 by a vacuum generator 11 for about 20 seconds. Further, when gas 22 in a cylinder 1 is exhausted on the delivery side 16, it is replaced with a new cylinder filled with gas. At the time, the inside of the primary pipe 14 is pressurized by the inert gas 15 for at least 10 seconds and then evacuated for about 20 seconds once manually just before a filling pipe 2 is removed from the cylinder 1.
This conventional method of purging remaining gas in the primary pipe 14 cannot sufficiently accomplish an intended end. That is, when the cylinder 1 is replaced, the inside of the pipe is corroded by the reaction of water in the atmosphere with the remaining gas. As a result, troubles are caused in parts such as respective air-operated valves and a pressure reducing valve. Further, actually, the filling pipe 2 is removed from the cylinder 1 in the state that gas is left and liberated in the primary pipe 14 for a long time because the cylinder 1 cannot be replaced just after the completion of purge of the remaining gas in the primary pipe 14, thereby leakage of gas is caused. Furthermore, the vacuum generator 11 is operated at all times while the inside of the primary pipe 14 is pressurized in the leaving-pipe-in-pressurized-state purge and the just-before-replacement purge, which increases the consumption of the nitrogen gas 17 for start.
Accordingly, an object of the present invention is to provide a cylinder cabinet capable of purging remaining gas in a primary pipe with high-efficiency and stopping a vacuum generator while the inside of the primary pipe is pressurized in leaving-pipe-in-pressurized-state purge and just-before-replacement purge and to provide a method of purging the remaining gas in the primary pipe.
According to the present invention, there is provided a cylinder cabinet comprising a cylinder containing gas and having a valve, a filling pipe, a primary pipe, a first air-operated valve, a pressure reducing valve, a secondary pipe, and a second air-operated valve through which the cylinder is connected to a supply side, a third air-operated valve through which inert gas flows into the primary pipe, and a vacuum generator to which the primary pipe is connected through a fourth air-operated valve and a pipe, wherein remaining gas in the primary pipe is purged by automatically repeating leaving-pipe-in-pressurized-state purge for pressurizing the inside of the primary pipe by the inert gas and leaving the pipe in the pressurized state for 2 to 10 minutes and evacuating the pipe for 20 seconds.
Further, according to the present invention, there is provided a method of purging remaining gas in a pipe in a cylinder cabinet comprising a cylinder cabinet containing gas and having a valve, a filling pipe, a primary pipe, a first air-operated valve, a pressure reducing valve, a secondary pipe, and a second air-operated valve through which the cylinder is connected to a supply side, a third air-operated valve through which inert gas flows into the primary pipe, and a vacuum generator to which the primary pipe is connected through a fourth air-operated valve and a pipe, the method comprising the step of purging remaining gas in the primary pipe by automatically executing leaving-pipe-in-pressurized-state purge for repeatedly pressurizing the inside of the primary pipe by the inert gas and leaving the pipe in the pressurized state for 2 to 10 minutes and evacuating the pipe for 20 seconds.